I am becoming a convert BACK to light-based AO, since SP3. It is mathematically more correct, because we really don't want to apply AO to lighting coming from directional lights, as they have correct shadows already. Since many of my earlier artifact problems seem to be gone, we can consider switching to that now.

With light-based AO, the amount of darkening is always corret as it only applies to the "ambient" light contributed by the IBL. In material based AO, we have to adjust the amount of darkening to reflect the proportion of light coming from our IBL, which of course varies from one scene to another.

However, since many of my shader users are on Poser 6, I will continue to supply shaders with built-in AO.

---

Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)